Electronic displays are now being installed throughout public sites for a number of different reasons (advertising, information, entertainment, menu boards, ticket counters, etc.). Of course, while installing electronic displays at public sites there must be adequate power present to drive the electronic displays. In some applications, multiple displays may be installed at a single location and it may not be feasible or desirable to establish individual circuits for each electronic display. Thus, it is now desirable for multiple electronic displays to share a single AC circuit.
However, when displays are used at public sites, especially outdoor environments or other situations where the ambient light levels are high, the light which is emitted from the display must compete with the amount of ambient light in the present environment. Thus, the displays may be required to produce a large amount of light in order to provide adequate picture quality for the environment. When multiple displays are installed on a single AC circuit, the ability for each display to produce large amounts of light (and draw large amounts of current) is limited by the maximum current level of the AC circuit. In many applications, the AC circuits being used for the displays are in areas where the AC circuit's maximum current may be on the order of 20 Amps.
It is typically undesirable to allow the installed displays to exceed the maximum current allowed by the AC circuit as this can typically lead to tripped breakers or blown fuses which can be time consuming and costly to reset or replace. Therefore, it is desirable to have multiple displays share a single AC circuit without exceeding the maximum current level allowed by the circuit. In other applications it may be desirable to limit the amount of current drawn by the displays for energy conservation reasons, rather than the limits placed on the circuit itself. Therefore, it is also desirable to group several displays together on a single circuit while limiting their power consumption in an effort to conserve energy.